100 years ago today – Earth got in the way of a small piece of cosmic debris, which exploded about 5 – 10 km from the ground. From Bad Astronomer: “The air blast flattened trees for hundreds of square kilometers. The ground shook, witnesses felt the hellish heat from kilometers away, and the shock wave circled the world.” And that was a small piece.

In case you missed Shelley’s awesome comment on the blog last week – you can now follow the Phoenix Mars Lander on Twitter, @MarsPhoenix. A recent post: “Want to see if subsurface ice shows evidence of periodic meltings &/or other indicators of possible past or present habitat for microbes.”